Environmental Thermal Stress Research Articles

Salivary heat shock protein 70 as a potential non-invasive biomarker of environmental thermal stress in dairy cattle

Salivary heat shock protein 70 as a potential non-invasive biomarker of environmental thermal stress in dairy cattle

Sexual selection buffers the negative consequences of population fragmentation on adaptive plastic responses to increasing temperatures.

Whether sexual selection facilitates or hampers the ability to plastically respond to novel environments might depend on population structure, via its effects on sexual interactions and associated fitness payoffs. Using experimentally evolved lines of the seed beetle Callosobruchus maculatus, we tested whether individuals evolving under different sexual selection (monogamy vs. polygamy) and population spatial structure (metapopulation vs. undivided populations) treatments differed in their response across developmental thermal conditions (control, hot, or stressful) in a range of fitness and fitness-associated traits. We found that individuals from subdivided populations had lower lifetime reproductive success at hot temperatures, but only in lines evolving under relaxed sexual selection, revealing a complex interaction between sexual selection, population structure, and thermal environmental stress on fitness. We also found an effect of population structure on several traits, including fertility and adult emergence success, under exposure to high thermal conditions. Finally, we found a strong negative effect of hot and stressful temperatures on fitness and associated traits. Our results show that population structure can exacerbate the impact of a warming climate, potentially leading to declines in population viability, but that sexual selection can buffer the negative influence of population subdivision on adaptation to warm temperatures.

Effect of heat mitigation strategies on the thermal environment of hardened pavement and pedestrian thermal comfort in a hot and humid area: A case study of Guangzhou, China.

The synergistic effect of heat waves and urban heat islands (UHI) adversely affect the urban environment, building energy consumption, and human health. The absorption and storage of short-wave radiation by hardened pavement is the primary reason for high-temperature heat waves and the UHI effect. Three mitigation strategies were assessed to alleviate the influence of high-temperature hardened pavement on the thermal environment and thermal comfort of pedestrians, water-spray vehicles (spray) and pavement watering (watering) to take advantage of evaporative cooling, and a fan based on convective heat transfer. In addition, the fan-spray and fan-watering combinations were evaluated to increase the evaporative cooling rate. Field measurements showed that the five heat mitigation strategies improved the thermal environment and reduced environmental thermal stress. The thermal sensation, comfort sensation, and mean skin temperature (MST) were analyzed in thermal perception experiments. The result indicated that the mitigation strategies changed the subjects' thermal perception. Moreover, regression analysis between the universal thermal climate index (UTCI) and the thermal response showed that the neutral temperature and the range of comfort threshold of UTCI and MST increased after implementing the mitigation strategies.

Motivational decline and proactive response under thermal environmental stress are related to emotion- and problem-focused coping, respectively: Questionnaire construction and fMRI study.

Despite the diversity of human behavioral and psychological responses to environmental thermal stress, the major dimensions of these responses have not been formulated. Accordingly, the relevance of these responses to a framework of coping with stress (i.e., emotion- and problem-focused) and the neural correlates are unexplored. In this study, we first developed a multidimensional inventory for such responses using social surveys and a factor analysis, and then examined the neural correlates of each dimension using a functional magnetic resonance imaging; we manipulated the ambient temperature between uncomfortably hot and cold, and the correlations between the inventory factor scores and discomfort-related neural responses were examined. We identified three factors to construct the inventory: motivational decline, proactive response, and an active behavior, which appeared to reflect inefficient emotion-focused coping, efficient problem-focused coping, and positive appreciation of extreme environmental temperatures, respectively, under environmental thermal stress. Motivational decline score was positively associated with common neural response to thermal stress in the frontal and temporoparietal regions, implicated in emotion regulation, while proactive response score negatively with the neural responses related to subjective discomfort in the medial and lateral parietal cortices, implicated in problem-solving. We thus demonstrated that two of three major dimensions of individual variation in response to and coping with environmental thermal stress conform to an influential two-dimensional framework of stress coping. The current three-dimensional model may expand the frontiers of meteorological human science in both basic and application domains.

Revealing the diversity of internal body temperature and panting response for feedlot cattle under environmental thermal stress

Core body temperature (CBT) regulation is crucial for mammalian wellbeing and survival. Cattle pant to dissipate excess heat to regulate CBT when ambient conditions exceed thermoneutral zones. However, to date, neither the variability in cattle heat response, the lagged response of CBT to thermal indices, nor the diurnal patterns of thermal indices, CBT and panting have been reported in the literature. We decomposed thermal indices, CBT and panting time-series data for 99 feedlot heifers across three discrete heat events into diurnal, trend and residual components. Both raw and decomposed data were analysed to explore the lagged CBT and panting responses and the association between series. We show ambient thermal conditions impact CBT with a 1-h lag despite a lag of between 1.5 to 3 h from raw data. Average individual panting scores were used to identify heat-susceptible and heat-tolerant cattle. Heat-susceptible cattle showed greater CBT (P < 0.01) between 8:00 and 23:00 and greater panting duration (P < 0.05) between 10:00 and 18:00 than heat-tolerant cattle under the same thermal conditions and these variations followed a similar pattern despite differences in cattle breed. This new information enables targeted amelioration and selection of individuals against heat susceptibility.

Effect of Electro-Thermo-Mechanical Coupling Stress on Top-Cooled E-Mode AlGaN/GaN HEMT

This work investigated the effects of single stress and electro-thermo-mechanical coupling stress on the electrical properties of top-cooled enhancement mode (E-mode) Aluminium Gallium Nitride/Gallium Nitride (AlGaN/GaN) high electron mobility transistor (HEMT) (GS66508T). Planar pressure, linear deformation, punctate deformation, environmental temperature, electro-thermal coupling, thermo-mechanical coupling, and electro-thermo-mechanical coupling stresses were applied to the device. It was found that different kinds of stress had different influence mechanisms on the device. Namely, excessive mechanical pressure/deformation stress caused serious, irrecoverable degradation of the device's leakage current, with the gate leakage current (Ig) increasing by ~107 times and the drain-to-source leakage current (Idss) increasing by ~106 times after mechanical punctate deformation of 0.5 mm. The device characteristics were not restored after the mechanical stress was removed. Compared with three mechanical stresses, environmental thermal stress had a greater influence on the device's transfer characteristic and on-resistance (Ron) but far less influence on Ig and Idss. As was expected, multiple stress coupled to the device promoted invalidation of the device. For more in-depth investigation, finite element simulation carried out with COMSOL was used to analyze the effect of electro-thermo-mechanical coupling stress on top-cooled E-mode AlGaN/GaN HEMT. The results of the experiments and simulation demonstrated that single and coupled stresses, especially mechanical stress coupled with other stresses, degraded the electrical properties or even caused irreversible damage to top-cooled E-mode AlGaN/GaN HEMT. Mechanical stress should be reduced as much as possible in the packaging design, transportation, storage, and application of top-cooled E-mode AlGaN/GaN HEMT.

Interdependency of Core Temperature and Glabrous Skin Blood Flow in Human Thermoregulation Function: A Pilot Study.

Human thermoregulation is governed by a complex, nonlinear feedback control system. The system consists of thermoreceptors, a controller, and effector mechanisms for heat exchange that coordinate to maintain a central core temperature. A principal route for heat flow between the core and the environment is via convective circulation of blood to arteriovenous anastomoses located in glabrous skin of the hands and feet. This paper presents new human experimental data for thermoregulatory control behavior along with a coupled, detailed control system model specific to the interdependent actions of core temperature and glabrous skin blood flow (GSBF) under defined transient environmental thermal stress. The model was tuned by a nonlinear least-squared curve fitting algorithm to optimally fit the experimental data. Transient GSBF in the model is influenced by core temperature, nonglabrous skin temperature, and the application of selective thermal stimulation. The core temperature in the model is influenced by integrated heat transfer across the nonglabrous body surface and GSBF. Thus, there is a strong cross-coupling between GSBF and core temperature in thermoregulatory function. Both variables include a projection term in the model based on the average rates of their change. Six subjects each completed two thermal protocols to generate data to which the common model was fit. The model coefficients were unique to each of the twelve data sets but produced an excellent agreement between the model and experimental data for the individual trials. The strong match between the model and data confirms the mathematical structure of the control algorithm.

Redox Status and Hematological Variables in Melatonin-Treated Ewes during Early Pregnancy under Heat Stress.

Simple SummaryHeat stress induces oxidative stress that negatively affects the fertility rate in farm animals, as it may disrupt normal follicular development and preimplantation embryogenesis. Although indigenous sheep breeds may exhibit adaptation to a certain level in high summer temperatures, their reproductive competence is still compromised under extreme severe heat stress conditions. Thus, the administration of melatonin is suggested, as an antioxidant regime, for improving the fertility rate and redox balance in heat-stressed ewes. The influence of environmental thermal stress in conjunction with melatonin treatment on hematological variables and cortisol secretion was also investigated. In this respect, melatonin seems to enhance the progressive adaptation of indigenous-breed ewes to environmental heat stress.The preovulatory follicles and preimplantation stage embryos are found to be rather sensitive to heat stress due to their low potential for scavenging reactive oxygen species (ROS). The aim of the present study was to assess the impact of melatonin administration on redox status and hematological variables during the preovulatory period and early stages of embryogenesis in heat-stressed ewes in vivo. Forty Karagouniko-breed ewes were divided in two groups, the melatonin (M, n = 20) group and control (C, n = 20) one. All animals were subjected to heat stress throughout the study, which lasted forty days (D0 to D40). In M group, melatonin implants were administered on D0. Then, oestrous synchronization was applied (D19-D33). On D34, six rams were introduced into the ewe flock for mating. Ultrasonographic examination was conducted on D73 for pregnancy diagnosis. The temperature humidity index (THI), the rectal temperature (RT), and the number of breaths per minute (BR) were evaluated twice daily. Redox biomarkers, namely total antioxidant capacity (TAC), reduced glutathione (GSH), and thiobarbituric acid reactive substances (TBARS), were assayed in blood samples collected on D0, D33, and D40. In addition, packed cell volume (PCV), white blood cells (WBCs), leukocyte differential count, and cortisol assessment were conducted in blood samples on D33 and D40. The results indicated improved fertility rate and mean number of lambs born per ewe due to improved redox status (p < 0.05) in ewes that received melatonin implants 34 days approximately before the onset of oestrus. The PCV decreased in both groups between the two time-points (p < 0.05). However, the NEU/LYMPH ratio decreased (p < 0.05) only in group M. The low cortisol levels and the decreased NEU/LYMPH ratio in both groups support the hypothesis that ewes of the indigenous Karagouniko breed may exhibit adaptation to environmental thermal stress. The administration of melatonin as an antioxidant regime may improve the reproductive competence of heat stressed ewes and may also enhance their ability to adapt at high ambient temperatures.

Performance of a directly deposited optical blocking filter on x-ray CCDs: case study from the REgolith X-ray Imaging Spectrometer (REXIS) experiment

The REgolith X-ray Imaging Spectrometer (REXIS) is a soft x-ray spectrometer and the student collaboration instrument aboard NASA’s OSIRIS-REx asteroid sample return mission. REXIS utilizes MIT Lincoln Laboratory CCID-41 x-ray detectors coated with a directly deposited optical blocking filter (OBF) with a thickness of 320 nm. The aluminum coating, developed at MIT Lincoln Laboratory, is designed to block visible light from the detector, to maintain high sensitivity to soft x-rays in the presence of reflected sunlight from the surface of the target asteroid Bennu. The scientific objective for the REXIS instrument is to measure the stimulated x-ray flux fluoresced from Bennu to discern elemental abundances present on the asteroid’s surface. The coating technique applied for blocking visible light had not previously been used on the CCD-41s in an extended space flight mission. The performance of the OBF on the flight detectors was not characterized before and after environmental stress testing. Therefore, to mature the OBF to technology readiness level (TRL) 6, the flight spare detectors were tested while the instrument was on the way to the asteroid. The flight spare hardware underwent vibration and thermal environmental stress testing to test the durability and effectiveness of the OBF. This testing informed our expectations of the in-flight OBF once it reached the asteroid and helped mature the TRL level of this directly deposited OBF. We discuss the setup and results of those tests and address the performance of the flight OBF at the asteroid. We conclude that depositing an aluminum OBF onto the surface of a charge-coupled device is able to withstand stresses of launch and an extended life-mission in interplanetary space.

Environmental Thermal Stress Induces Neuronal Cell Death and Developmental Malformations in Reptiles.

SynopsisEvery stage of organismal life history is being challenged by global warming. Many species are already experiencing temperatures approaching their physiological limits; this is particularly true for ectothermic species, such as lizards. Embryos are markedly sensitive to thermal insult. Here, we demonstrate that temperatures currently experienced in natural nesting areas can modify gene expression levels and induce neural and craniofacial malformations in embryos of the lizard Anolis sagrei. Developmental abnormalities ranged from minor changes in facial structure to significant disruption of anterior face and forebrain. The first several days of postoviposition development are particularly sensitive to this thermal insult. These results raise new concern over the viability of ectothermic species under contemporary climate change. Herein, we propose and test a novel developmental hypothesis that describes the cellular and developmental origins of those malformations: cell death in the developing forebrain and abnormal facial induction due to disrupted Hedgehog signaling. Based on similarities in the embryonic response to thermal stress among distantly related species, we propose that this developmental hypothesis represents a common embryonic response to thermal insult among amniote embryos. Our results emphasize the importance of adopting a broad, multidisciplinary approach that includes both lab and field perspectives when trying to understand the future impacts of anthropogenic change on animal development.

Effects of heat hardening on life parameters and thermostability of Bradysia odoriphaga larva and adults

AbstractEnvironmental temperature is an important factor restricting insect population dynamics. Due to the ongoing global warming, interest in the impact of heat stress on insects has grown. High temperature in summer is a key barrier for Bradysia odoriphaga (Diptera: Sciaridae), a devastating vegetable pest o in China. It is well known that moderate thermal hardening can enhance the thermotolerance of many insects, which is beneficial for adaptation to environmental thermal stress. In order to determine whether heat hardening was beneficial for B. odoriphaga to adapt to high summer temperatures, we studied the biological performance, antioxidant responses and hsp70 and hsp90 expression of B. odoriphaga 4th instar larvae and adults after pre‐exposure to mild heat hardening temperatures (30–36°C). Mild heat hardening (32–36°C) enhanced the larval thermal tolerance to extreme heat stress. However, life parameters were significantly inhibited, development was delayed, longevity was shortened, and fecundity was decreased. Mild heat hardening (30–34°C) caused serious adverse effects on life parameters and less enhancement of heat resistance for 4th instar larvae. Mild heat hardening at 36°C weakened the heat tolerance of adults. The activity of four antioxidant enzymes in B. odoriphaga changed dramatically after heat hardening at 32–36°C. During recovery at 25°C, catalase (CAT), peroxidase (POD) and glutathione‐S‐transferase (GST) in tested larvae maintained successive higher activities after heat hardening. Simultaneously, the expression levels of hsp70 and hsp90 increased significantly after thermal hardening. Higher expression levels were also detected in larvae, pupae and adults after 48 hr recovery at 25°C. Overall, mild heat hardening played an important role in heat tolerance plasticity of B. odoriphaga larvae, and the antioxidant system and hsp70 and hsp90 genes were extremely relevant to this adaptation process.

Suppressing Thermal Negative Effect and Maintaining High-Temperature Steady Electrical Performance of Triboelectric Nanogenerators by Employing Phase Change Material.

Triboelectric nanogenerators (TENGs) are newly developed energy-harvesting mechanisms, which can efficiently transmute irregular mechanical energy into scarce electrical energy. However, the electrical performance of TENGs shows a decreasing tendency with the increase in temperature, and the negative effect caused by friction heat and operating environmental thermal stresses for the output performance, durability, and reliability are still a bottleneck, restricting the practical application of TENG electronic devices. Especially for wearable TENG devices, the heat-induced temperature rise evokes extreme discomfort and even hazards to human health. To effectively suppress the thermal negative effect and maintain the high-temperature steady electrical performance of TENGs, a novel thermo-regulating TENG (Tr-TENG) based on phase change materials (PCMs) is designed. The results state clearly that the Tr-TENG can maintain steady output performance without deterioration by the introduction of PCMs, during continuous heating and natural cooling, while the output performance of conventional TENG is decayed by 18.33%. More importantly, the Tr-TENG possesses high-efficiency thermal management ability, resulting in its improved durability, reliability, and thermal comfort. This study creates new possibilities for the development of advanced multifunctional TENGs with attractive characteristics and desirable performances and promotes the application of TENG electronic devices in harsh environments.

Temperature change in steel-concrete composite bridge: Experimental and numerical study

In this article, a prototype empirical section of the composite girder was performed to verify the temperature distributions and the changes in concrete bridges under environmental thermal stresses. T-Beam composite section was placed directly subjected to environmental conditions to endure the change in convection, the convection includes solar radiation, surrounding air temperature and wind speed. In addition, this paper includes the 3D finite-element thermal studies represented by the COMSOL MULTIPHYSIC program, with particular reference to the influence of several parametric studies that represented by changing in concrete thickness, adding asphalt layer and finally change the value of wind speed. The section is prepared with fifteen thermocouples in different places in steel and concrete in the actual and theoretical model to evaluate the temperature distribution inside the composite bridges and their effects in the selected points. COMSOL MULTIPHYSIC showed a good ability to simulate convection, heat conduction and radiation within the surrounding environment. Such as thermocouple (TC3) the minimum temperature was 33.18 oC, 33.29 oC, the maximum temperature was 63.67 oC, 62.77 oC for experimental and theoretical results respectively while the maximum and minimum difference between experimental and FE temperatures is 2.96 and 0.099 for TC3 respectively. Therefore, it can be said that all the thermocouples results showed a good agreement between practical and theoretical results.

Spatiotemporal variations on infrared temperature as a thermal comfort indicator for cattle under agroforestry systems.

With the expanding use of thermal assessment techniques in beef cattle, infrared thermography has become a promising tool for assessing the environment for animal thermal comfort. Goals of this study were: (1) to evaluate cattle thermal comfort in agroforestry systems with different shade availability (2) to verify the spatiotemporal variations of infrared temperature inside agroforestry systems, and; (3) to test infrared thermography as a potential tool to assess animal thermal comfort indices in agroforestry systems. A trial was carried out between June 2015 and February 2016, covering Central-Brazil's dry winter and rainy summer seasons, respectively. The experimental area of Embrapa Beef Cattle is located in Campo Grande (Mato Grosso do Sul), coordinates 20°24'53″ S, 54°42'26″ W and 558m altitude. The 12ha plot has two agroforestry systems varying shade availability. Traditional Black Globe Temperature and Humidity Index, Heat Load Index and Radiation Thermal Load were determined, from measurements using digital thermo-hygrometers, with datalogger. Surface temperature and humidity of tree canopies and pasture were determined using an infrared thermographic camera. Results show spatiotemporal variations in infrared temperature. This means that the environment inside agroforestry systems is not homogeneously comfortable for cattle, and the system with the lowest shade availability has the greatest heat accumulation area. Weak to strong associations were identified between infrared variables and thermal comfort indices (0.08=r≤0.75). Positive relationships were also obtained and equally well explained by the Black Globe Temperature and Humidity Index and Heat Load Index (0.55=R2≤0.94). We conclude that infrared thermography can be used as a tool to assess thermal comfort indices in agroforestry systems and to determine onset of animal thermal stress from environment and heat body accumulation.

خنک سازی محیطهای شهری و تأثیر آن بر تغییرات اقلیمی در محلات سنتی و سکونتگاههای غیررسمی از طریق آسایش حرارتی بیرونی (نمونه موردی محلات عاملی ، قلعه ساختمان و شهرک حجت شهر مشهد)

خنک سازی محیطهای شهری و تأثیر آن بر تغییرات اقلیمی در محلات سنتی و سکونتگاههای غیررسمی از طریق آسایش حرارتی بیرونی (نمونه موردی محلات عاملی ، قلعه ساختمان و شهرک حجت شهر مشهد)

Seasonal cellular stress responses of commercially important invertebrates at different habitats of the North Aegean Sea

In many aquatic species, the negative effect of temperature variations has a significant impact on physiological performance since beyond Tp (upper pejus) and Tc (critical temperatures), according to the oxygen- and capacity-limited thermal tolerance (OCLTT), transition to hypoxemia and mitochondrial metabolism triggers the increase in reactive oxygen species (ROS) production. However, climate change may have different spatial impact, and as a result, areas with more favorable climatic conditions (refugia) can be identified. The aim of the present study, based on cellular stress responses, is the demarcation of these areas and the preservation of commercially important marine species. Under this prism, individuals of the species Callinectes sapidus (blue crab), Sepia officinalis (common cuttlefish), Holothuria tubulosa (sea cucumber) and Venus verrucosa (clam) from Thermaikos, Pagasitikos and Vistonikos gulf were collected seasonally. The results showed an increase in the levels of several stress indicators exhibiting the triggering of Heat Shock Response, MAPK activation, apoptotic phenomena and increased ubiquitilination during the summer sampling in relation to the spring and autumn samplings concerning blue crab and clam, while no changes were observed for common cuttlefish and sea cucumber. It seems that these cellular responses consist a cytoprotective mechanism against environmental thermal stress. Regarding collection sites, for all examined species, higher cellular stress levels were observed in Pagasitikos, and lower in Vistonikos gulf. This analysis of biochemical and molecular markers is expected to provide a clearer picture for the definition of “refugia” for the above species.

Hydroxyproline-Rich Glycoproteins as Markers of Temperature Stress in the Leaves of Brachypodium distachyon.

Plants frequently encounter diverse abiotic stresses, one of which is environmental thermal stress. To cope with these stresses, plants have developed a range of mechanisms, including altering the cell wall architecture, which is facilitated by the arabinogalactan proteins (AGP) and extensins (EXT). In order to characterise the localisation of the epitopes of the AGP and EXT, which are induced by the stress connected with a low (4 °C) or a high (40 °C) temperature, in the leaves of Brachypodium distachyon, we performed immunohistochemical analyses using the antibodies that bind to selected AGP (JIM8, JIM13, JIM16, LM2 and MAC207), pectin/AGP (LM6) as well as EXT (JIM11, JIM12 and JIM20). The analyses of the epitopes of the AGP indicated their presence in the phloem and in the inner bundle sheath (JIM8, JIM13, JIM16 and LM2). The JIM16 epitope was less abundant in the leaves from the low or high temperature compared to the control leaves. The LM2 epitope was more abundant in the leaves that had been subjected to the high temperatures. In the case of JIM13 and MAC207, no changes were observed at the different temperatures. The epitopes of the EXT were primarily observed in the mesophyll and xylem cells of the major vascular bundle (JIM11, JIM12 and JIM20) and no correlation was observed between the presence of the epitopes and the temperature stress. We also analysed changes in the level of transcript accumulation of some of the genes encoding EXT, EXT-like receptor kinases and AGP in the response to the temperature stress. In both cases, although we observed the upregulation of the genes encoding AGP in stressed plants, the changes were more pronounced at the high temperature. Similar changes were observed in the expression profiles of the EXT and EXT-like receptor kinase genes. Our findings may be relevant for genetic engineering of plants with increased resistance to the temperature stress.

Oocyte quality and heat shock proteins in oocytes from bovine breeds adapted to the tropics under different conditions of environmental thermal stress

In order to evaluate the influence of thermal stress on physiological parameters, and the oocyte quality of Girolando (n = 12) and adapted Pantaneira (n = 12) cattle, twelve sessions of ultrasound guided follicular aspiration (OPU) were performed, between January and November 2014 (during dry (May–September) and rainy season (October–April) in Brazil). The recovered cumulus-oocyte complexes (COCs) were selected and classified, according to quality, immediately after OPU. The oocytes were then stored in 3% paraformaldehyd before conducting immunofluorescence analysis under confocal microscopy to identify HSP70 and 90 proteins. Before each OPU session, the rectal temperature (RT) and respiratory frequency (RF) of each animal were measured. The black globe humidity index (BGHI) was calculated on the day of the OPUs and 90 days before each OPU session, and related to the thermal stress of the animals. The quality of oocytes from Girolando cattle, but not Pantaneira, showed a negative relationship with BGHI of 90 days before OPU. RT of both breeds did not exceed normal values for cattle below BGHI 95. BGHI variation on the day of OPU did not affect RF of the adapted Pantaneira breed (p = 0.3221). On the other hand, Girolando cattle showed a positive relationship between RF and BGHI (p = 0.0103). With increasing BGHI, the amount of HSP70 increased in Girolando oocytes, however, decreased in the Pantaneira breed. We have not observed a relationship between HSP 90 and BGHI, however Girolando cattle produced a greater amount of this protein in relation to the Pantaneira breed. In conclusion, higher BGHIs, 90 days before OPU session, negatively affect oocyte quality of Girolando cattle and positively affect oocyte quality of the Pantaneira breed. Higher BGHIs on the day of the OPU session negatively affected the respiratory frequency of the Girolando breed, and lead to a higher recruitment of HSP70 to protect oocyte maturation. The opposite pattern was observed for Pantaneira. In addition, Pantaneira cattle produced twice as much as HSP70 as Girolando cattle, suggesting that a natural higher production of this protein could be involved in the mechanisms of adaptation to heat conditions.

Effect of environmental thermal fatigue on concrete performance based on mesostructural and microstructural analyses

An environmental thermal fatigue (ETF) test method was proposed here. Porosimetry and quantitative microcrack analysis was used to evaluate the effect of mesostructural changes in the cement matrix and interfacial transition zone (ITZ) on the mechanical performance of concrete under ETF. The morphology, thermal behavior, and chemically bound water content were further used to study the mechanisms behind the mesostructural changes. A mesomechanical model based on the porosity and microcracks was proposed based on the relationship between the mesostructural parameters and mechanical performance. Damage caused by environmental thermal fatigue stresses and strengthening due to rehydration reactions occurred simultaneously. The mechanical performance first increased and then decreased with increasing ETF cycles due to rehydration reactions strengthening the cement matrix, followed by an increase in Ca(OH)2 content that degraded the strength due to deterioration of the ITZ structure. The pore structure first refined and then coarsened. Microcracks were mainly located in the ITZ and were enhanced with increasing ETF cycles, where this enhancement was more obvious in the late of ETF.

Biophysical Spandrels form a Hot-Spot for Kosmotropic Mutations in Bacteriophage Thermal Adaptation.

Temperature plays a dominating role in protein structure and function, and life has evolved myriad strategies to adapt proteins to environmental thermal stress. Cellular systems can utilize kosmotropic osmolytes, the products of complex biochemical pathways, to act as chemical chaperones. These extrinsic molecules, e.g., trehalose, alter local water structure to modulate the strength of the hydrophobic effect and increase protein stability. In contrast, simpler genetic systems must rely on intrinsic mutation to affect protein stability. In naturally occurring microvirid bacteriophages of the subfamily Bullavirinae, capsid stability is randomly distributed across the phylogeny, suggesting it is not phylogenetically linked and could be altered through adaptive mutation. We hypothesized that these phages could utilize an adaptive mechanism that mimics the stabilizing effects of the kosmotrope trehalose through mutation. Kinetic stability of wild-type ID8, a relative of ΦX174, displays a saturable response to trehalose. Thermal adaptation mutations in ID8 improve capsid stability and reduce responsiveness to trehalose suggesting the mutations move stability closer to the kosmotropic saturation point, mimicking the kosmotropic effect of trehalose. These mutations localize to and modulate the hydrophobicity of a cavern formation at the interface of phage coat and spike proteins-an evolutionary spandrel. Across a series of genetically distinct phages, responsiveness to trehalose correlates positively with cavern hydrophobicity suggesting that the level of hydrophobicity of the cavern may provide a biophysical gating mechanism constraining or permitting adaptation in a lineage-specific manner. Our results demonstrate that a single mutation can exploit pre-existing, non-adaptive structural features to mimic the adaptive effects of complex biochemical pathways.